Preparation And Properties Of Conductive And Magnetic Composites

Nowadays multifunctional composites with electrical conductivity and magnetic property are widely applied in biomedical fields as well as military camouflage and so on because of their unique properties,suah as not only can eliminate static electricity,but also have a good effect on electromagnetic interference(EMI)shielding and microwave absorption.In this work,we mainly study the synthesis and property of magnetic particles as well as electromagnetic composite materials,including the particles and fiber with electrical conductive and magnetic property,systematically.The NdFeB magnetic particles were obtained by a Sol-Gel process,and the Fe3O4 and Co doped Fe3O4 nanoparticles(Co-Fe3O4)were obtained by a chemical coprecipitation process.The effect of Co content on the magnetic property of Co-Fe3O4 was studied through the analysis of the magnetic test.It is found that when the molar ratio of Fe3+:Fe2+:Co2+ was 2:1:0.5,the magnetic property can reach the optimum value with a saturation magnetization of 64.55emu/g and the coercive force and remanence of 8.66emu/g and 175.340e,respectively.The electromagnetic nanocomposites with a core-shell structure were synthesized by in situ chemical oxidative polymerization,in which the Co-Fe3O4 act as the core and the poly(3,4-ethylenedioxythiophene)-poly(sodium-p-styrenesulfonate)(PEDOT-PSS)as the conductive polymer shells.The effect of the molar ratio of Co-Fe3O4 to EDOT monomer(written as[Co-Fe3O4]:[EDOT])on the electromagnetic properties was systematically investigated.The structure' and properties of the nanocomposites were characterized by SEM,TEM,VSM and conductivity test,respectively.The results show that the nanocomposites present a laminated core-shell composite structure,the conductivity increased with the increase of EDOT monomer ratio,the maximum conductivity reach to 2.96S/cm at the molar[Co-Fe3O4]:[EDOT]of 1:7.6.The saturation magnetization(Ms)of nanocomposites decreases with the increase of EDOT monomer ratio,the maximum of saturation magnetization up to 41.95emu/g at the molar[Co-Fe3O4]:[EDOT]of 1:0.95.Polyvinyl alcohol(PVA)was chosen as the matrix,PEDOT-PSS and Co-Fe3O4 were used as conductive and magnetic component respectively.The PEDOT-PSS/Co-Fe3O4/PVA composite fibers with conductive and magnetic properties were obtained via a conventional wet spinning process.Effects of PEDOT-PSS and Co-Fe3O4 content and draw ratio on the properties of composite fibers were investigated.The results show that with the increase of the draw ratio,the composite fiber's conductivity,crystal properties,thermal stability and mechanical properties were all improved.When the content of magnetic particles is 2.68wt%and the content of PEDOT-PSS is 8.6wt%,the saturation magnetization of the composite fiber is about 1.7emu/g.When the composite fiber's draw ratio is 4,the conductivity can reach to 2.3 S/cm.